Amusement parks often employ pyrotechnic compositions in the form of colorful fireworks. Unfortunately, the burning of large quantities of such pyrotechnics can generate large amounts of smoke and depending upon the particular weather conditions, such as wind direction, wind speed and relative humidity, the smoke can block the view of further fireworks or can envelop the audiences.
Fireworks projectiles typically include two components, an initial burst and a main burst. Black powder is one of the oldest pyrotechnic compositions and is typically used in both the initial burst and the main burst. The main burst also includes smaller color-producing pellets referred to as "stars". Igniting these stars during detonation of the main burst provides the light and color of a fireworks display. Among typical compositions for a red star have been: (1) potassium chlorate, strontium carbonate, charcoal, red gum (shellac), and dextrin (or rice starch); (2) potassium perchlorate, strontium carbonate, charcoal, red gum (or shellac), dextrin (or rice starch) and polyvinyl chloride; or (3) strontium nitrate, red gum (or shellac), magnalium (an alloy of aluminum and magnesium) and Parlon.RTM. chlorinated rubber (C.sub.6 H.sub.6 Cl.sub.4).sub.n. Unfortunately, all such typical compositions generate various quantities of smoke.
One low-smoke pyrotechnic composition including a high-nitrogen content, low-carbon content energetic material from the group of dihydrazino-s-tetrazine, derivatives of dihydrazino-s-tetrazine and salts of dihydrazino-s-tetrazine, an oxidizing agent, and a colorant was described by U.S. Pat. No. 5,917,146, entitled "High-Nitrogen Energetic Material Based Pyrotechnic Compositions" by Hiskey et al. As dihydrazino-s-tetrazine materials are relatively expensive, the search for other low-smoke pyrotechnic compositions has continued.
Additional efforts have dealt with a search for replacement colorants to be used in low smoke pyrotechnic compositions in place of previous colorants such as cupric oxide, barium nitrate, strontium nitrate and the like. U.S. Patent No. 5,682,014 by Highsmith et al. describes metal salts of a bitetrazoleamine such as bis-(1(2)H-tetrazol-5-yl)-amine (BTA) as non-azide fuels for gas generant compositions.
It is an object of this invention to provide a low smoke pyrotechnic composition, preferably an essentially smoke-free pyrotechnic composition.
Another object of the present invention is to provide a pyrotechnic composition including a high-nitrogen content, low-carbon content energetic material.
Another object of the present invention is the use of metal salts of a high-nitrogen content, low-carbon content energetic material as a colorant in a pyrotechnic composition.
Still another object of the present invention is an improved blue emitting pyrotechnic composition.